Atomic Force Microscopy and Force Spectroscopy

The species Corynebacterium glutamicum is a non-pathogenic soil bacterium with great biotechnological importance. Discovered in the 1950s in Japan as a superior natural producer of glutamic acid, C. glutamicum is nowadays massively used for industrial production of amino acids, which are employed as flavour enhancers in food as additive to cattle feed and pharmaceutical products. Moreover, C. glutamicum is used as non-pathogenic model-organism for related human pathogens such as Corynebacterium diphtheriae, Mycobacterium tuberculosis and Mycobacterium leprae. Due to its economic value, investigations on this species have aroused broad interest over the last decades. Their cell surface structure represents one of the main characteristics of C. glutamicum, the so-called S-layer. In the context of this work, it has become possible to image for the first time the hexagonal cell surface lattice on living C. glutamicum with molecular resolution in atomic force microscopy (AFM)-topographies recorded in air and in AFM-images recorded in liquid. The development of immobilisation methods of the bacterial cells to enable AFM-imaging in air and liquid represent a major part in this study.